Swift extension of Sequence to check if an intersection exists

Question

My goal is to have a function available through all Sequence like Array or Set.

This function should return a Bool telling whether there is at least one object present in both sequences or not.

// Usage
let s1 = ["hi", "hey", "ho"]
let s2:Set = ["woop", "oi", "yes"]

if s2.intersects(with: s1) {
  print("Happy me, it's a match")
}

extension Sequence where Element:Equatable {
    func intersects<T:Sequence>(with anotherSequence:T) -> Bool
    where T.Element: Equatable {
        //                  ⬇ error: `Extraneous argument label 'where:' in call`
        return self.contains(where: anotherSequence.contains)
    }
}

// doing the same function outside works:
let rez = s1.contains(where: s2.contains)
print(rez)

I feel like I'm almost there but I don't understand why the first contains(where:) gives me this error. Both contains() and contains(where:) belongs to Sequence no?

What am I missing?

Answer 1

Well I found the correct syntax, not sure why the other syntax would not work tho :/

If someone could still explain why the other way does not work, it'd be interesting 🤔

extension Sequence where Element:Equatable {
    func intersects<T:Sequence>(with anotherSequence:T) -> Bool
        where T.Element == Self.Element {
        return self.contains(where: anotherSequence.contains)
    }
}